a. Field of the Invention
The present invention relates to a shutter blade assembly for focal plane shutters of a type using shutter blades.
B. Description of the Prior Art
Generally, a focal plane shutter of a type using shutter blades is constituted as follows. That is to say, a pair of arms of the same length are each pivoted at one end in a spaced relationship to a shutter plate having an exposure aperture. A shutter blade for forming an exposure slit is pivoted to the respective other ends of these arms so that a parallelogram link mechanism is formed by the pair of arms and the shutter blade. Accordingly the exposing operation is made by parallelly moving the shutter blade with respect to the exposure aperture.
In the focal plane shutter of this type, if the distance separating the arms of the pair, that is, the distance between the respective pivoting points is too short, when the shutter blade moves, an undesirable backlash or fluctuation is likely to occur. Therefore, the separating distance of the arms of the pair can not be shortened excessively. Therefore a camera equipped with this type of focal plane shutter is comparatively large, particularly when a single-lens reflex camera using a pentaprism is equipped with this kind of focal plane shutter. In such a case, the dimension in the vertical direction is remarkably large.